Self Build Advice Please - consumer units, sockets & switches...

[janner43]

Hi all,

We are doing a self build 2 bed bungalow in Devon which is going to be very highly insulated with u-values of..
Floor 0.15
Walls 0.14
Ceiling 0.11

With an air tightness factor of 0.8
MVHR with 89% efficiency

* Our other design spec includes no central heating system (not required with the previous specs), we'll just add a panel heater to act as a top up for the stored heat within the home when required. The MVHR should do the rest.

* An "experiment" with no central hot water - just local instantaneous water heaters (3 @ 12kw) where required. Half the plumbing, no dead leg of water, no waste hot water stored. We are not having a bath, so an instantaneous electric shower (9.5kw)

* We are having a 3.7kw solar array. The whole concept is based on the PassivHaus model with a couple of tweaks.

I don't really want to debate the design concepts - feel free to comment if you like, though .
The whole idea has been predicated on thinking differently about the designs when it comes to the heating and water heating together with an avoidance of the connection costs, plumbing, boiler purchase, boiler servicing costs associated with a gas connection (which is available).

We have a great, fully qualified sparky on the project who grew up with our son & is a good guy. I know he'll give us good advice, but I would appreciate several points of view on this please. He is kindly not supplying materials & is letting me source those to save some money. He is also arranging for a pal with the MCS ticket to commission the solar array at mates rates.

That's the background, now to the questions...

1) Consumer Unit...
I wondered if it would be a good idea to have two consumer units...
One for the heavy items - three 12kw water heaters and one 9.5kw shower
One for everything else

Or just get one large unit?

Would there be an issue with the solar array connectivity if we had two consumer units?

I like the idea of splitting as many of the circuits as possible, so what sort of config would you design if this was your build?

2) What brands are the best value for money - I'm familiar (Dad was an electrician for decades, started his trade in the 1950s) with MK, Wylex - but are they as good now as they were or are other names just as good?

3) Any recommendation on which make of sockets & switches to get?

4) Any recommendations as to the cheapest place to buy the gear from please? I already have a Trade Account at Travis Perkins (and Trade Point - don't laugh, it might be handy... )

I hope I have given you enough information & thanks in advance for taking the time to read this and for any answers / opinions / recommends you might be willing to give.

Cheers all.

 

[davesparks]

Regarding question 2, I've found the quality of terminal screws on the earth and neutral bars in more recent Wylex boards to be poor (though I haven't fitted one of the new metal ones). Crabtree Starbreaker are made by the same company as Wylex but are much better quality and the MCBs and RCBOs plug in (quicker installation and arguably a safer product) though they cost a bit more. The MK boards are pretty cheap but a reasonable quality and better in my view than other similarly priced boards I've seen from BG and others. I've only seen plastic Schneider boards and not the new metal ones but as a respected forum member like Davesparks rates them I'll probably give one a go myself at some point.

I don't fit Wylex, Crabtree or any other electrium stuff since they recalled mcbs when they started catching fire a few years ago

Note I said DB rather than CU, the Schneider CUs aren't particularly great but their DBs (acti 9/Merlin Gerin) are the dogs dangles

 

[janner43]

Op, please excuse me, but I have suspicious nature. I'm just wondering if your electrician really exist? If you have a 'fully qualified sparky' on the project, then most of the questions you're asking, could easily be answered by him. Some of the ways you have replied, are like the royal 'We'. I'm aware of self build projects, where the owners take on most if not all of the different trades. There are self build forums dedicated for that purpose. I question the viability of having 3 x 12kw instantaneous water heaters and a 9.5kw shower, albeit there's only two of you, it may overload your supply. If are considering some of ths work yourself, it may be you should consider asking joining the DIY part of this forum, where you questions will still receive a good response.

I don't mind the question at all. I can understand why you are asking it, too. But your suspicions are unfounded. I like to be informed and to glean wisdom from a number of sources. As far as doing some work myself, then yes, I'll be installing the kitchen, laying the oak floor throughout and doing all the decorating. I'll also be doing all the garden greenscaping and planting.

The electrics, plumbing and plastering are all subbed out. If the thread is in the wrong section, my apologies and perhaps if a mod agrees with that, then they would be so kind as to move it.

I can also understand you questioning the viability of the water heaters. I could have specced lower kW models, but given the water heating is something of an experiment, that's what we are going with. If they prove too large, I'll swap one or two out. Could have specced all sorts of things - ground source heat pumps, air source heat pumps, solar water heating - mains gas is also available.

I could have looked at other solutions too - such as an electric boiler, but that would miss out on the avoidance of long pipe runs etc. It would also miss the point of a serious thought process of how much hot water anyone actually uses from a tap these days. With a dishwasher and a washing machine, and no bath the amount of water to be run at any one time is no more than a couple of litres at worst - and then only occasionally.

As far as any future owners are concerned, I'll leave them to worry about how they heat water. We are building a home for us for the rest of our lives, not some type of investment vehicle.

I know some of the design is a little left field for the UK, but it isn't an unusual way of doing things everywhere in the world.

 

[joehat]

BANG!! , Main Fuse!!

Over and out!!

 

[Octopus]

There's nothing worse than a "self build" project manager buying kit off the internet. I charge my hourly rate for ALL issues and time spent wasted or on resolutions I have to do.......or even wait for parts to arrive!

Just saying

 

[janner43]

BANG!! , Main Fuse!!

Over and out!!

For Normal domestic 100Amp Fuses to BS 1361, these are the graph given figures of TIME V. CURRENT, to Rupture the fuse:-
0.1 second @ 1800Amps
1 second @ 950Amps
5 seconds @ 630Amps
3 MINUTES @ 360Amps
10 MINUTES @ 250Amps - (Fuse does get Hot)
1 HOUR @ 170Amps

 

[davesparks]

For Normal domestic 100Amp Fuses to BS 1361, these are the graph given figures of TIME V. CURRENT, to Rupture the fuse:-
0.1 second @ 1800Amps
1 second @ 950Amps
5 seconds @ 630Amps
3 MINUTES @ 360Amps
10 MINUTES @ 250Amps - (Fuse does get Hot)
1 HOUR @ 170Amps

You should not plan an installation which relies on this though, the fuse will weaken with time as it is subjected to such overloads and the terminals etc of the cutout won't necessarily be rated for the duty.

 

[hasel5]

Use the gas supply simples

 

[janner43]

Use the gas supply simples

Sigh...


Urban.co.uk News and Views Blog | Flame goes out for gas in the UK


The UN's Paris climate deal 'signals end to gas cookers' say experts | Daily Mail Online


Huge change facing property world as gas looks set to be phased out - Property Industry Eye


and this from 2014...
Forget your gas cooker ? we?re headed for 'zero carbon? Britain - Telegraph

 

[7029 dave]

On your opening post, you say the Electrician will be advising you, does that mean he is not working on the installation.?

 

[janner43]

You should not plan an installation which relies on this though, the fuse will weaken with time as it is subjected to such overloads and the terminals etc of the cutout won't necessarily be rated for the duty.

I agree.

I cannot see anything more than 26kw (113amp) ever being used at once - and then only on rare occasions and only for 90 seconds maximum. But I must admit that I would have been happier if the water heaters were on the smaller side, but have decided to go with these (already bought)

 

[janner43]

On your opening post, you say the Electrician will be advising you, does that mean he is not working on the installation.?

He is doing all the electrical work. Perhaps I should have been more semantically correct and said "I know he will give us good advice and perform an excellent & professional service for us"

Good grief, I am beginning to wish I hadn't asked!!

 

[davesparks]

Sigh...


Urban.co.uk News and Views Blog | Flame goes out for gas in the UK


The UN's Paris climate deal 'signals end to gas cookers' say experts | Daily Mail Online


Huge change facing property world as gas looks set to be phased out - Property Industry Eye


and this from 2014...
Forget your gas cooker ? we?re headed for 'zero carbon? Britain - Telegraph

Yeah right, our electricity networks are a patchwork of ancient cables and distribution waiting to fall apart. A mass move to electric heating and cooking will result in one heck of a lot of power cuts!

 

[jackhammerJIM]

Good grief, I am beginning to wish I hadn't asked!!

Your on here for advice which is being given . It is just advice "do whatever you want to "

 

[janner43]

You should not plan an installation which relies on this though, the fuse will weaken with time as it is subjected to such overloads and the terminals etc of the cutout won't necessarily be rated for the duty.

I agree.

I cannot see anything more than 26kw (113amp) ever being used at once - and then only on rare occasions and only for 90 seconds maximum. But I must admit that I would have been happier if the water heaters were on the smaller side, but have decided to go with these (already bought)

You have made me think though Dave. I will give some consideration to a 3kw 5litre hot water solution for the kitchen. It is the kitchen tap which will be used most and possibly at the same time as the shower (9.5kw) or a bathroom tap (12kw).

 

[janner43]

Yeah right, our electricity networks are a patchwork of ancient cables and distribution waiting to fall apart. A mass move to electric heating and cooking will result in one heck of a lot of power cuts!

It isn't what we think about it that matters though Dave, is it. Apparently that is a serious proposal that is being considered - I know it seems hard to believe, but I only know what I have read...